Massive yet elegant, the great structure of the Mosque-Madrassa of Sultan Hassan is regarded as the finest piece of early-Mamluk architecture in Cairo. It was built between 1356 and 1363 by the troubled Sultan Hassan, a grandson of Sultan Qalaun; he took the throne at the age of 13, was deposed and reinstated no less than three times, then assassinated shortly before the mosque was completed. Tragedy also shadowed the construction when one of the minarets collapsed, killing some 300 onlookers. Beyond the striking, recessed entrance, a dark passage leads into a square courtyard whose soaring walls are punctured by four iwan s (vaulted halls), one dedicated to teaching each of the four main schools of Sunni Islam. At the rear of the eastern iwan, an especially beautiful mihrab is flanked by stolen Crusader columns. To the right, a bronze door leads to the sultan’s mausoleum.